Fix v18 tablets removed from healthcheck when topo server GetTablet call fails #201
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…all fails Signed-off-by: Brendan Dougherty <[email protected]>
shanth96
reviewed
Nov 6, 2024
| @@ -190,6 +190,17 @@ func (tw *TopologyWatcher) loadTablets() { | |||
| topologyWatcherOperations.Add(topologyWatcherOpGetTablet, 1) | |||
| <-tw.sem // Done; enable next request to run | |||
| if err != nil { | |||
| if !topo.IsErrType(err, topo.NoNode) { | |||
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Would the error be a NoNode even when it's a network partition?
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No, the NoNode error means the path does not exist in zookeeper. We would get a NoNode error if the tablet was removed from the topo server between the call to get all the tablet aliases (tw.getTablets(tw)) and the call to get that tablet (tw.topoServer.GetTablet(tw.ctx, alias)). So we allow the tablet to be removed from the healthcheck on a NoNode error.
austenLacy
reviewed
Nov 7, 2024
shanth96
approved these changes
Nov 7, 2024
austenLacy
approved these changes
Nov 7, 2024
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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…thcheck-on-topo-error Fix v18 tablets removed from healthcheck when topo server GetTablet call fails (cherry picked from commit a46ede6)
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This is the v18 fix for this bug: vitessio#15632
The code for getting tablets for healthchecks was significantly altered between v18 and v19, so even though the bug is similar, the fix is different.
Description
In v18,
TopologyWatcher.loadTablets()roughly works like this:newTabletsmapnewTabletsnewTablets:tw.tablets(the current set of tracked tablets)tw.tablets(the current set of tracked tablets)newTabletsSo the bug in v18 is that if a GetTablet call fails, the tablet is not added to
newTablets, and thus removed from the healthcheck when iteratingtw.tablets.Changes
TopologyWatcher.loadTablets()to handle GetTablet errors by backfillingnewTabletswith the current value fromtw.tablets. This is the same approach used in the v19+ fix.TestGetTabletErrorDoesNotRemoveFromHealthchecktest from the v19+ fixTestGetTabletNoNodeErrorRemovesFromHealthcheckto cover the case where a tablet is removed from the topo server bewteen the call togetTabletsand the call toGetTabletfor that alias. That scenario is handled differently in v19+ so I added explicit handling for it in this fix.